Lightweight Aggregate Concrete

Lightweight Aggregate Concrete

King Abdullah Financial District

Rayadah Investment Company is building King Abdullah Financial District (KAFD), a 1.6 million square meters (sqm) real estate development located north of Riyadh. KAFD includes the Saudi Stock Exchange (Tadwul), the Capital Market Authority (CMA) and the Commodity Market headquarters.

Project Requirements:

The project requires to isolate the building slabs and sidewalks with a 10 mm thickness layer of lightweight aggregate concrete with the following characteristics:

Characteristic Strength = 20 MPa @ 28 days

Maximum Density = 1800 kg/m³

Slump 150±50 mm

Challenges:

Light weight aggregate not available in Riyadh

Achieve the Strength 20 Mpa @ 28 days with low density

Due to the nature of lightweight aggregate, the concrete mix will exhibit high resistance to pumpability to higher level (high absorption nature of high porosity aggregate reduces the water amount that designed in the mix).

Since pumping this type of mix usually reduces the air content in the mix, the concrete density tends to increasing

Controlling the mix yield and maintaining the mix characteristics during delivery, handling and placing.

The conventional concrete with slump 150±50 mm will exhibition difficulties during pumpability to high rise

Solutions:

Lightweight aggregate (Cicolite) form the Western Region were used in the lightweight mix

Reducing the cement content, which has a high density characteristic, in the mix

Using Microsilica in the mix to achieve the required strength and the density , which in contrast with cement, has a low density Characteristic

Use of air entraining admixtures to maintain the air content as desired.

Aggregates were saturated to improve the pumpability of the mix to higher levels

The conventional concrete with slump 150±50 mm was modified to Self-Compacting Concrete with 550±50 mm to insure the pumpability of the mix to high rise level

High flowable grout was pumped through pipelines to insure full internal capsulation for pipeline to facilitate the pumpability and to control the maintaining of the mix characteristics during pumping process.